In brief, this is a field in which scientists look for patterns of shared traits among individuals that have different levels of shared genes and infer relatedness and genetic influence from that. The basic notion being that if you have a behavioral trait that is more common the closer you are genetically, you can infer that the behavior is driven by the person's genes. Because of concerns over the environment's effects, the studies focus on several variants that help control for environmental influence. For example, comparing identical twins to fraternal twins or comparing siblings that are raised in different environments. Unfortunately this approach has flaws. For example, he notes that monozygotic twins and dizygotic twins are not treated the same; the environment is much more similar for monozygotic twins. The environmental differences can start early - if they split within the first five days after conception each will have its own placenta. If they split in the 5-10 day range, there is a shared placenta. This means there will be a difference in the extent to which they share the same bloodstream.
He mentions a Johns Hopkins study that examined differences in math ability between boys and girls. The data set suggested that boys were better than girls at math, with a 13:1 ratio in the upper levels. However, in more equal societies, such as our friendly Scandanavians, the difference is not only diminished, but slightly reversed with girls scoring higher. The lower a society's score when it comes to gender equality, the greater the difference between the sexes on tests of mathematical aptitude.
Alas, at this point in time coughing girl comes on to the scene. She'll be coughing in the background for the next few lectures. Thanks a million coughing girl.
As he notes the differences in environment for 13 year old boys and girls, it's easy to see that his viewpoint is that this field is, at the very least, difficult to prove scientifically and, more realistically, ludicrous. Simply put, people don't ever share the same environment. There are thousands of different experiences that shape us and influence how we handle situations.
To correct for this, adoption studies are used. Here siblings with similar genes that are raised in different environments are compared. The thinking is relatively straightforward - if these siblings are more like each other than they are like the siblings in their adoptive homes, genes are playing a role.
A big study on schizophrenia based on Danish citizens shows genetic influence in the development of schizophrenia. Using adoption studies and statistical measures, they found a 1% chance of being schizophrenic among the population on the whole, but with no biological basis while being raised in a schizophrenic household the number goes up to 3%. When raised in a household that did not have a schizophrenic parent but in which the biological parent(s) do, the number jumps to 9%. And for the truly bizarre situation in which the kid had a genetic legacy of schizophrenia and managed to get adopted into a household with a schizophrenic adoptive parent, the rate goes all the way to 17%. He notes that this synergistic effect will come up again. Sapolsky also states that this study was the first time a genetic basis was shown for a psychological disorder. As such it's a landmark event because a genetic psychological problem is a medical problem, not just a mere adjustment to society issue.
But there are problems.
1. Under the cleanest circumstances the baby would have been whisked away seconds after birth, thus preventing any shared environment with the mother. However, this is not often the case.
2. Prenatal effects - the prenatal environment shared with mom, including levels of various hormones in the bloodstream.
To get around this (perhaps speciously) the argument is made that they can measure the frequency with which the trait is shared with the mother or father. If there's a 17% correlation with the mom but only 10% with the father, then the 7% difference is attributed to the prenatal effects.
3. Adoptive family placements are not random. Efforts are made to place the child in a similar type of home. Thus the adoptee shares a lot of biology with the new family, screwing up the notion that environment and genetics have been separated.
The new gold standard study model is the identical twins separated at birth model. From this group, the research suggests about 50% heritability of IQ, about 50% heritability of where you are on the introversion-extroversion scale, and about 50% heritability for degree of aggression.
Anxiety levels as an adult can be impacted by the prenatal environment (in rats). The more stressed the mother, the higher the glucocorticoid levels in the bloodstream, resulting in a smaller brain, thinner cortex, more glucocorticoid receptors, fewer benzodiazepine receptors, more of a decline in cognitive ability as you age and a harder time bouncing back from stress - meaning more cumulative exposure to glucocorticoids and therefore more damage. This can be referred to as non-Mendelian inheritance of traits since the thinking is that it's not a genetic thing.
Holland 1944 and the Dutch Hunger Winter. The Nazis divert all the food in Holland to Germany. The Dutch diet thus goes from normal to starvation level. 3rd trimester fetuses develop super thrifty metabolisms due to nutrient deficiency and thus become much more likely (19 fold increase in risk) to develop metabolic diseases such as diabetes, obesity, high blood pressure, etc. because their bodies keep a greater than normal percentage of nutrients - sugar, sodium, fat - all stored. They in turn have offspring who are at a greater risk because the mothers' thrifty metabolisms don't share as freely with their offspring.
Fetal Origins of Adult Disease (FOAD).
Interestingly, the poor Russians at Stalingrad did not demonstrate a similar pattern because their starvation went on much longer and showed a pattern of slow but steady decrease followed by a slow rise. Incidentally, Antony Beevor's Stalingrad is an excellent book.
A study with transplanted rat fetuses demonstrated that the fetus took on the characteristics of the placental mom - when she was high anxiety, the rat was high anxiety, regardless of the genes of the true mom.
Mitochondria, the powerhouse of the cell, have their own DNA and along with other junk in the cell split somewhat randomly during gamete formation. Mitochondria only come from the mother's side.
Indirect genetic traits. Judith Rich Harris and The Nurture Assumption. Here the question is to what extent the environment acts on genetic traits in order to reify them. To wit, where you are on the extroversion/introversion scale is as much a result of how the world interacts with you as it is your genes. Thinking in terms of a good looking baby and an ugly baby - both have extrovert genes but only one of them gets a lot of smiles back in response to extroverted behavior. Other genetic factors will mediate the impact of the gene in question as well the world at large.
Continuing with the example, he points out that height is a heritable trait to a significant extent and that endless studies have shown that taller people are treated better and considered more attractive, "comma, he says bitterly."
Not surprisingly, people who are treated better during the developmental periods end up being more extroverted. Thus with have heritability of a trait that in turn causes you to be treated differently in the world which brings about changes in personality. Again, the genes are having a hard time winning out on their own.
The pecking order - you inherit the color and iridescence of your feathers. Get bad feathers, you get pecked at more often and head to the bottom of the social ladder.
Studies have suggested 70% heritability of political preferences in the US. However, this is actually mediated by personal characteristics, especially comfort with ambiguity. Conservatives tend to not like ambiguity, preferring black and white analyses of situations. He then transitions into the Kohlberg scale of moral development and the notion that there's a theory that tries to link up political preferences with one's stage of moral development. In both examples, conservatives end up looking pretty bad - simplistic worldview and under-developed morals. This is one area where Professor Sapolsky may be presenting a biased view. While your author agrees with him in many ways, the conservative viewpoint has its nuances and there are issues for which adding in ambiguity may be possible but not necessarily smart (crime, for example, which endless studies have shown is significantly impacted by SES and all kinds of developmental elements - yet and still, there's still a crime that's been committed and the why doesn't undo it - is ambiguity correct here? I'm not taking a stance, but am noting that it's an area of ethical debate in which ambiguity isn't necessarily the winner).
Curiously, studies showing heritability of aggression in rats actually have an underlying mediating factor - pain sensitivity. The more aggressive rats are less able to tolerate pain and thus more likely to lash out aggressively when they feel it. Again, the surface behavior is not the one that's being passed along.
Mothering styles of rats impact the robustness of the rat as an adult. Better mothering leads to a healthier rat that's likely to be a good mother when grown. This is accomplished through epigenetic changes in transcription factors.
He mentions a Johns Hopkins study that examined differences in math ability between boys and girls. The data set suggested that boys were better than girls at math, with a 13:1 ratio in the upper levels. However, in more equal societies, such as our friendly Scandanavians, the difference is not only diminished, but slightly reversed with girls scoring higher. The lower a society's score when it comes to gender equality, the greater the difference between the sexes on tests of mathematical aptitude.
Alas, at this point in time coughing girl comes on to the scene. She'll be coughing in the background for the next few lectures. Thanks a million coughing girl.
As he notes the differences in environment for 13 year old boys and girls, it's easy to see that his viewpoint is that this field is, at the very least, difficult to prove scientifically and, more realistically, ludicrous. Simply put, people don't ever share the same environment. There are thousands of different experiences that shape us and influence how we handle situations.
To correct for this, adoption studies are used. Here siblings with similar genes that are raised in different environments are compared. The thinking is relatively straightforward - if these siblings are more like each other than they are like the siblings in their adoptive homes, genes are playing a role.
A big study on schizophrenia based on Danish citizens shows genetic influence in the development of schizophrenia. Using adoption studies and statistical measures, they found a 1% chance of being schizophrenic among the population on the whole, but with no biological basis while being raised in a schizophrenic household the number goes up to 3%. When raised in a household that did not have a schizophrenic parent but in which the biological parent(s) do, the number jumps to 9%. And for the truly bizarre situation in which the kid had a genetic legacy of schizophrenia and managed to get adopted into a household with a schizophrenic adoptive parent, the rate goes all the way to 17%. He notes that this synergistic effect will come up again. Sapolsky also states that this study was the first time a genetic basis was shown for a psychological disorder. As such it's a landmark event because a genetic psychological problem is a medical problem, not just a mere adjustment to society issue.
But there are problems.
1. Under the cleanest circumstances the baby would have been whisked away seconds after birth, thus preventing any shared environment with the mother. However, this is not often the case.
2. Prenatal effects - the prenatal environment shared with mom, including levels of various hormones in the bloodstream.
To get around this (perhaps speciously) the argument is made that they can measure the frequency with which the trait is shared with the mother or father. If there's a 17% correlation with the mom but only 10% with the father, then the 7% difference is attributed to the prenatal effects.
3. Adoptive family placements are not random. Efforts are made to place the child in a similar type of home. Thus the adoptee shares a lot of biology with the new family, screwing up the notion that environment and genetics have been separated.
The new gold standard study model is the identical twins separated at birth model. From this group, the research suggests about 50% heritability of IQ, about 50% heritability of where you are on the introversion-extroversion scale, and about 50% heritability for degree of aggression.
Anxiety levels as an adult can be impacted by the prenatal environment (in rats). The more stressed the mother, the higher the glucocorticoid levels in the bloodstream, resulting in a smaller brain, thinner cortex, more glucocorticoid receptors, fewer benzodiazepine receptors, more of a decline in cognitive ability as you age and a harder time bouncing back from stress - meaning more cumulative exposure to glucocorticoids and therefore more damage. This can be referred to as non-Mendelian inheritance of traits since the thinking is that it's not a genetic thing.
Holland 1944 and the Dutch Hunger Winter. The Nazis divert all the food in Holland to Germany. The Dutch diet thus goes from normal to starvation level. 3rd trimester fetuses develop super thrifty metabolisms due to nutrient deficiency and thus become much more likely (19 fold increase in risk) to develop metabolic diseases such as diabetes, obesity, high blood pressure, etc. because their bodies keep a greater than normal percentage of nutrients - sugar, sodium, fat - all stored. They in turn have offspring who are at a greater risk because the mothers' thrifty metabolisms don't share as freely with their offspring.
Fetal Origins of Adult Disease (FOAD).
Interestingly, the poor Russians at Stalingrad did not demonstrate a similar pattern because their starvation went on much longer and showed a pattern of slow but steady decrease followed by a slow rise. Incidentally, Antony Beevor's Stalingrad is an excellent book.
A study with transplanted rat fetuses demonstrated that the fetus took on the characteristics of the placental mom - when she was high anxiety, the rat was high anxiety, regardless of the genes of the true mom.
Mitochondria, the powerhouse of the cell, have their own DNA and along with other junk in the cell split somewhat randomly during gamete formation. Mitochondria only come from the mother's side.
Indirect genetic traits. Judith Rich Harris and The Nurture Assumption. Here the question is to what extent the environment acts on genetic traits in order to reify them. To wit, where you are on the extroversion/introversion scale is as much a result of how the world interacts with you as it is your genes. Thinking in terms of a good looking baby and an ugly baby - both have extrovert genes but only one of them gets a lot of smiles back in response to extroverted behavior. Other genetic factors will mediate the impact of the gene in question as well the world at large.
Continuing with the example, he points out that height is a heritable trait to a significant extent and that endless studies have shown that taller people are treated better and considered more attractive, "comma, he says bitterly."
Not surprisingly, people who are treated better during the developmental periods end up being more extroverted. Thus with have heritability of a trait that in turn causes you to be treated differently in the world which brings about changes in personality. Again, the genes are having a hard time winning out on their own.
The pecking order - you inherit the color and iridescence of your feathers. Get bad feathers, you get pecked at more often and head to the bottom of the social ladder.
Studies have suggested 70% heritability of political preferences in the US. However, this is actually mediated by personal characteristics, especially comfort with ambiguity. Conservatives tend to not like ambiguity, preferring black and white analyses of situations. He then transitions into the Kohlberg scale of moral development and the notion that there's a theory that tries to link up political preferences with one's stage of moral development. In both examples, conservatives end up looking pretty bad - simplistic worldview and under-developed morals. This is one area where Professor Sapolsky may be presenting a biased view. While your author agrees with him in many ways, the conservative viewpoint has its nuances and there are issues for which adding in ambiguity may be possible but not necessarily smart (crime, for example, which endless studies have shown is significantly impacted by SES and all kinds of developmental elements - yet and still, there's still a crime that's been committed and the why doesn't undo it - is ambiguity correct here? I'm not taking a stance, but am noting that it's an area of ethical debate in which ambiguity isn't necessarily the winner).
Curiously, studies showing heritability of aggression in rats actually have an underlying mediating factor - pain sensitivity. The more aggressive rats are less able to tolerate pain and thus more likely to lash out aggressively when they feel it. Again, the surface behavior is not the one that's being passed along.
Mothering styles of rats impact the robustness of the rat as an adult. Better mothering leads to a healthier rat that's likely to be a good mother when grown. This is accomplished through epigenetic changes in transcription factors.
